Arrangement in rapping mechanisms for emission electrodes in electrical precipitators



S. LAGERDAHL May 18, 1965 ARRANGEMENT IN RAPPING MECHANISMS FOR EMISSION ELECTRODES IN ELECTRICAL PRECIPITATORS Filed Oct. 15, 1962 mveuron: SEBASTIAN LAGERDAHL WWW ATTYS.

United States Patent 3,183,648 ARRANGEMENT IN RAPPING MECHANISMS FOR EMISSION ELECTRODES IN ELECTRICAL PRECIPITATORS Sebastian Lagerdahl, Johanneshov, Sweden, assignor to Aktiebolaget Svenska Fliiktfabriken, Stockholm, Sweden Filed Oct. 15, 1962, Ser. No. 230,561 Claims priority, application Sweden, Oct. 27, 1961, 10,7 26/ 61 2 Claims. (Cl. 55-112) This invention relates to an arrangement in rapping mechanisms for emission electrodes in electrical precipitators. In the present embodiment of the invention a rapping mechanism comprises a horizontal shaft equipped with hammers and rotatably driven by a driving means disposed outside the precipitator, the driving means being electrically insulated from the shaft by an intermediate insulating shaft.

For maintaining the insulating capacity of the intermediate insulating shaft, it is of special importance to prevent dust leakage out through the shaft passage opening enabling accumulation on and about the insulating shaft. Dust buildup in this manner causes interruptions by electrical flash-overs.

This invention has as its primary object elimination of the above mentioned drawback and at the same time keeping the insulating shaft as Well as the adjacent shaft ends free of any dust accumulation.

In the present instance the insulating shaft is enclosed in a chamber connected to the precipitator opening into the precipitator housing. The chamber includes a hood enclosing the insulating shaft, the outer periphery of which is a sutficient distance from the non-insulated portion of the shaft to prevent arcing The hood is fastened to and rotates with the shaft of the driving means and has the shape of a truncated cone, the open end of which diverges towards the precipitator a scraping iron projects into the cone and is mounted on a rigid side wall of the precipitator while extending along the entire envelop surface of the cone thereby forming an angle with the generatrix of the inner surface.

Other objects and a fuller understanding of the invention may be had by referring to the following description and claims taken in conjunction with the accompanying drawing in which:

The drawing is a fragmentary sectional view through a side elevation of a portion of an electrical precipitator embodying the present invention.

Referring now to the drawing, a rapping mechanism ice outer casing and fastened to and rotating with the shaft of the driving means, has the shape of a truncated cone, the open end of which diverges towards the interior of the electrical precipitator. A scraping iron 7 projects into the cone and is secured onto the precipitator 5. In the present instance the scraping iron 7 has a length substantially equal to the length of a side wall of the cone and is mounted obliquely in relation to the generatrix of the inner surface and in scraping engagement therewith.

What I claim is:

1. In an electrical precipitator, including a side wall having an opening therein, a rapping mechanism for cleaning emission electrodes in said electrical precipitator, said rapping mechanism comprising a rotatable shaft extending into said precipitator through said opening, at least one hammer connected to said rotatable shaft in said precipitator for striking said emission electrodes upon rotation of said shaft, driving means outside said precipitator for rotating said shaft, an intermediate insulating shaft connecting said driving means to said shaft, an outer casing enclosing said insulating shaft and closing said opening to prevent dust leakage out of said precipitator, an inner casing having substantially the shape of an open ended truncated cone diverging towards the interior of said precipitator and connected to and rotating with said driving means, said inner casing being located within said outer casing, and a scraping iron mounted on said precipitator in scraping engagement With the inner surface of said inner casing thereby preventing dust accumulation on said inner surface upon rotation of said shaft, said inner casing positioned with its open end adjacent said opening whereby dust removed by said iron falls into said precipitator.

2. Apparatus in accordance with claim 1 wherein said scraping iron forms an angle with the generatrix of said inner surface.

References Cited by the Examiner UNITED STATES PATENTS 1,122,460 12/14 Anderson 210-373 1,253,037 1/18 Horstmann 210-373 X 1,463,352 7/23 Weiskopf 55--112 X 1,903,298 4/33 Roberts 210-376 X 2,547,573 4/51 Gannone 55-112 2,694,464 11/54 Wintermute 55152 2,864,459 12/58 Gustafsson 55--112 FOREIGN PATENTS 713,691 8/31 France.

427,537 4/26 Germany.

490,186 1/30 Germany.

505,794 8/30 Germany.

565,152 10/33 Germany.

HARRY B. THORNTON, Primary Examiner.

ROBERT F. BURNETT, Examiner. 

1. IN AN ELECTRICAL PRECIPITATOR, INCLUDING A SIDE WALL HAVING AN OPENING THEREIN, A RAPPING MECHANISM FOR CLEANING EMISSION ELECTRODES IN SAID ELECTRICAL PRECIPITATOR, SAID RAPPING MECHANISM COMPRISING A ROTATABLE SHAFT EXTENDING INTO SAID PRECIPITATOR THROUGH SAID OPENING, AT LEAST ONE HAMMER CONNECTED TO SAID ROTATABLE SHAFT IN SAID PRECIPITATOR FOR STRIKING SAID EMISSION ELECTRODES UPON ROTATION OF SAID SHAFT, DRIVING MEANS OUTSIDE SAID PRECIPITATOR FOR ROTATING SAID SHAFT, AN INTERMEDIATE INSULATING SHAFT CONNECTING SAID DRIVING MEANS TO SAID SHAFT, AN OUTER CASING ENCLOSING SAID INSULATING SHAFT AND CLOSING SAID OPENING TO PREVENT DUST LEAKAGE OUT OF SAID PRECIPITATOR, AN INNER CASING HAVING SUBSTANTIALLY THE SHAPE OF AN OPEN ENDED TRUNCATED CONE DIVERGING TOWARDS THE INTERIOR OF SAID PRECIPITATOR AND CONNECTED TO AND ROTATING WITH SAID DRIVING MEANS, SAID INNER CASING BEING LOCATED WITHIN SAID OUTER CASING, AND A SCRAPING IRON MOUNTED ON SAID PRECIPITATOR IN SCRAPING ENGAGEMENT WITH THE INNER SURFACE OF SAID INNER CASING THEREBY PREVENTING DUST ACCUMULATION ON SAID INNER SURFACE UPON ROTATION OF SAID SHAFT, SAID INNER CASING POSITIONED WITH ITS OPEN END ADJACENT SAID OPENING WHEREBY DUST REMOVED BY SAID IRON FALLS INTO SAID PRECIPITATOR. 